1. Field of the Invention
The present invention relates to switches used in telecommunication networks, and more specifically to a method and apparatus for efficiently supporting point to multipoint applications.
2. Related Art
Point to multipoint applications generally refer to applications in which the same data is transferred from a single source to multiple destinations. In an example scenario, a service provider transmits data forming a video stream (e.g., movies) on a network to multiple subscribers. The network in turn may be formed by several switches (with connecting paths), which may need to support the transmission of the data.
In one prior approach, a dedicated point-to-point PVC may be provided from the single source to each of the subscribers. One problem with such an approach is that the resulting solution may not scale to large environments containing potentially many thousands of subscribers because a corresponding number of point-to-point PVCs would be needed to be supported from the single source.
The problem may be exacerbated due to the fact that valuable resources such as buffer space in a switch and/or bandwidth on a path/link (connecting switches), may need to be allocated to each of the PVCs irrespective of whether the PVC is in use or not. Allocation of resources to such point-to-point PVCs may prevent support for more PVCs in general.
In an alternative approach, a point-to-point SVC may be provided from a single source to each of the subscribers. As a point-to-point SVC is generally set up only when needed and released (terminated) otherwise, resources may not be dedicated between the source and each subscriber. As a result, the available resources may be optimally used to potentially support a large number of subscribers.
However, one problem with such an alternative approach is that the same data may be transmitted on each of the multiple point-to-point SVCs, and the available bandwidth may not be sufficient to support a large number of subscribers. Another typical problem with the above noted approach is that the overhead of setting up and terminating SVC connections between the source and subscribers may be unacceptably high.
Accordingly, in another prior approach, a point-to-multipoint SVC may be provided from a single source to each of the subscribers. Data to be transferred is duplicated at the source and sent to multiple subscribers. However, the signaling overhead due to the dynamic creation and dropping of unwanted connections between the source and the subscribers may still be unacceptably high. Another problem with the above noted approach is that there may be a time lag in the setting up of the SVC. As a result of the time lag data may be lost during the setting up of SVC. Loss of data while configuring SVC may also be undesirable at least in some environments.
Therefore, what is needed are a method and apparatus for efficiently supporting point to multipoint applications.